1. Field of the Invention
This invention relates to a safety syringe having a disposable, prefilled medication carpule and a combination needle retaining hub and needle cannula, and to a slide lock which is connected to the carpule and movable from a needle retaining position, at which the cannula is anchored so as to project axially from the carpule for administering an injection, to a needle releasing position, at which the cannula may be retracted within and completely shielded by the carpule.
2. Prior Art
Syringes of the type having a prefilled carpule of fluid medication and a hypodermic needle cannula are well known in the art for injecting such medication from the carpule to a targeted tissue area of a patient. However, at the completion of the injection, the needle is typically locked in an axially extended position projecting outwardly from the syringe cylinder. In some cases, the syringe may be used to treat a patient having a communicable disease. Prior to disposing the syringe, the hypodermic needle is frequently broken or destroyed to prevent reuse. Medical workers are especially susceptible to accidental and potentially infectious needle strikes due to the careless handling or breaking of the needle cannula and disposing of the syringe after use. The resulting mini-accident caused by an accidental needle strike typically requires a blood test for such diseases as AIDS and hepatitis. The corresponding cost and inefficiency of testing medical workers who have received such an accidental needle strike result in considerable waste, which may be particularly damaging to a medical facility which is striving for economy.
The following patent application, which has been or will be assigned to the assignee of the present patent application, discloses a syringe including a prefilled medication carpule and means for retracting a needle cannula into said carpule after an injection has been administered: application Ser. No. 143,751 filed January 14, 1988 by Terry M. Haber et al.